Flexible Truck Modeling and Investigation of Coupling Between Rigid and Flexible Dynamics

摘要

Inclusion or omission of flexible frame effects in truck models is often based on intuition or assumption. Flexibility is typically incorporated via a computationally costly finite element model, or a linear lumped-parameter or modal expansion model that assumes small motions. In the latter case, the number of modes to retain is rarely determined systematically. A pitch-plane bond graph model is presented which includes longitudinal dynamics and transverse frame vibration. Large rigid body motions are allowed, onto which small flexible vibrations are superimposed. Motive forces can be defined to propel the truck forward over varying terrain, including hills. Frame flexibility is incorporated using modal expansion of a free-free beam. The model is then subjected to a power-based proper modeling method and response surface analysis to determine the number of required flexible modes, and the range of validity of a rigid model. Frame flexibility could not be neglected for outputs such as payload acceleration that were directly related to transverse frame vibration. Retaining the first bending mode but eliminating higher modes gave acceptable errors regardless of road roughness or load. Retaining the first and second bending modes gave negligible error for all combinations of parameters in the study.